--- a/contrib/perf.py	Wed Feb 07 13:49:02 2018 +0530
+++ b/contrib/perf.py	Sun Feb 04 10:28:03 2018 +0900
@@ -1088,7 +1088,7 @@
         for left, right in textpairs:
             # The date strings don't matter, so we pass empty strings.
             headerlines, hunks = mdiff.unidiff(
-                left, '', right, '', 'left', 'right')
+                left, '', right, '', 'left', 'right', binary=False)
             # consume iterators in roughly the way patch.py does
             b'\n'.join(headerlines)
             b''.join(sum((list(hlines) for hrange, hlines in hunks), []))